William sent in this link – https://phys.org/news/2019-05-newly-fossil-footprints-paleontologists-re… … newly discovered fossil footprints force paleontologists to rethink ancient desert inhabitants. The footprints were discovered in a remote part of the Grand Canyon National Park – see for instance www.sciencedaily.com/releases/2018/11/181108142448.htm … and https://www.nps.gov/grca/learn/news/newly-discovered-fossils.htm … A large sandstone boulder contains some well preserved tracks of primitive tetrapods (four footed animals) which are said to have inhabited an ancient desert environment back in the Permian period. However, a reappraisal of the footprints decided the tracks belonged to along extinct relative of the reptiles and similar tracks are also known from Europe. These are the ichniotheriums. They had short legs and a large body. These animals were not extected to live in a desert environment as they were not independent of water. In spite of this paleontologists were sure they were living in a desert so they have simply updated what they think are able to survive in desert conditions.